Synergistic insecticidal compositions



United States tent O SYNERGISTIC INSECTICIDAL COL [POSITIONS No Drawing. Original application Mar. 24, 1955, Ser. No. 496,596. Divided and this application Oct. 15, 19 58, Ser. No. 767,286

2 Claims. (Cl. 167-30) This invention relates broadly to insecticidal compositions, and more particularly to insecticidal compositions containing phenyl N-methylcarbamate and 0,0-diethyl O-(4-m'trophenyl) thiophosphate, hereinafter referred to as Parathion. More particularly, this invention relates to synergistic insecticidal compositions of these compounds wherein the insecticidal effectiveness of each component is enhanced by the presence of the other to produce an unexpected combined effect.

When two or more substances in combination show an unexpectedly high activity, as, for instance, insecticidal activity, the resulting phenomenon is called synergism. The mechanism of synergism is by no means understood. It is, in fact, quite probable that it differs with diiferent synergistic combinations. The term synergism can be defined, however, as a cooperative action which is encountered in combinations of two or more biologically active components in which the combined activity of the two components exceeds the sum of the activities of the components when used alone. The insecticidal activity of the mixed components cannot be predicted from known values of the individual components, but is unpredictable and depends on the individual activity of neither.

It is an object of this invention to provide insecticidal compositions of enhanced killing power. Another object of this invention is to produce novel compositions containing compounds capable of synergizing the knockdovm and killing properties of individual toxicants. A further object of this invention is to provide compositions including a relatively toxic phosphorus containing insecticide in which superior insecticidal activity is obtained because of the synergistic effects, but in which the ultimate toxicity to warm-blooded animals is greatly reduced because of the lower concentrations of the phosphorous compounds required when used in combination with the relatively less toxic carbamates. Other objects and advantages of the invention will become apparent from the description of the invention set forth below.

According to this invention, there are provided synergistic insecticidal compositions comprising 0,0-diethyl O- (4-nitrophenyl) thiophosphate, hereafter called Parathion, and phenyl N-methylcarbamate. This carbamate may be prepared as described in copending application Serial No. 812,113, filed May 11, 1959.

The synergistic insecticidal compositions of this invention may be used on a wide variety of insect and mite species, but are particularly effective against Mexican bean beetles. The combinations are highly effective and economical to use for such large-scale insecticidal requirements as the control of truck crop, forage crop and orchard insects.

The synergistic compositions of this invention can be formulated as aqueous emulsions, as dry or wettable powders, as solutions or in any other suitable vehicle. The insecticidal compositions can be utilized as sprays,

2,961,371 Patented Nov. 22, 1960 as dusts, as aerosol mixtures, insecticidal coating compositions, and as residues. In general, they canbe applied by methods commonly used for'control'or eradication of insects, mites and th elike. Thus these insecticidal com positions can beformulatedwith solvents, diluents and carrier media, adhesives, spreadingwetting. and emulsifying agents and other ingredients.

The relative proportions of the active ingredients :as well as inert carriers, solvents, dispersants and the like may vary within wide limits. I

Thus the relative proportion (ratio) of the Parathion to the phenyl N-methylcarbamate can range from 20 parts of the former per 1 part of the latter to 1 part of the former per 40 parts of the latter and preferably about 1 part of the former to about 4 parts of the latter.

The quantities of the component toxicants in the final insecticidal compositions can range from 0.01% to 25.00% for the Parathion and from 0.05% to 50;00% for the carbamate, and preferably frorn 0.10% to 10.00% for the Parathion and from 0.10% to 25.00% for the carbamate. s

The procedures of the testing method are described below. The details of the test experiments including the type of formulation and mode of application or dosing, and the species of insects which served as test subjects are given in the examples.

The test method used is described as follows:

DUST TOWER METHOD This general method is described in the following reference, Moore, J. Econ. But. 43, No. 2, 188-190 (1950).

The dusting apparatus consists of a vertical glass cylinder, 34 inches high and 8.5 inches in diameter, into which the appropriate dust sample is discharged through a small hole in the center of the cover, by means of a small laboratory duster operating at an air pressure of 40 p.s.i.g. The duster assembly comprises a 10 ml. beaker, into which the Weighed sample is placed, and fitted with a rubber stopper through which pass the air inlet and dust outlet tubes, both of which are made of 4 inch diameter copper tubing. At the outer end of the air inlet tube is a trigger valve that serves as a control for dispensing the dust. The inner end of this tube reaches nearly to the bottom of the beaker. The end of it is sealed but, along the sides, seven 0.032 inch holes are drilled at irregular intervals which serve as air inlets. Such an arrangement causes pronounced turbulence of the dust and thus insures exhausting the complete sample from the beaker. The dust outlet tube forms an arch from the top of the beaker to the top of the glass dusting tower.

After discharge of the sample into the tower, there is allowed a 2-minute settling time before removal of foliage or insects being treated. A weighed metal plate is placed in the tower each time a test is made, and by weighing the amount of dust deposited on it, it is then possible to calculate the amount applied per acre.

Because of day-to-day variations in the results obtained by this test method, comparisons among the individual components and their combinations were made simultaneously in order to minimize this source of variation.

Slight modifications in this test employed for specific insect species are as noted below.

Mexican berm beetle-In tests using this insect, bean foliage was dusted then infested with fourth instar Mexican bean beetle larvae. These were allowed to feed for 24 hours, then treated foliage was replaced with untreated. Mortality records were made at 48 hours.

Table 1 Dust Dust Rats Mortality Oonc. Cone. (LbsJ Test Method Test Subject (Percent) (Percent) (Percent) acre) Phenyl N-methylcarhamate.. 1 Dust Tower-.- Mexican bean beetle..- 0 Do Parathlon.. U. 25 do do 22 D0 1 do. 0.25 do --d0 100 This table demonstrates the unexpected effectiveness of the insecticidal compositions of this invention against the Mexican bean beetle.

This application is a division of co-pending application Serial No. 496,596, filed March 24, 1955, now abandoned, which is a continuation-in-part of Serial No. 15

four parts of said carbamate per part of said thiophosphate.

References Cited in the file of this patent UNITED STATES PATENTS Jelinek Apr. 11, 1950 Gysin May 25, 1954 OTHER REFERENCES King: US. Dept. Agr. Handbook No. 69, May 1954,

Chemical Age, vol. 63, No. 163 (1950), p. 540. Sharp: Agr. News Letter, January-February 1952, pp. 1-3.

Roark: US. Dept. Agr. Bull. 13-344 (May 1935), pp.

Frear: Chem. of the Pesticides, 3rd Ed., January 1955, pp. 73-91. 

1. SYNERGISTIC INSECTICIDAL COMPOSITIONS COMPRISING O,O-DIETHYL O-(4 NITROPHENYL) THIOPHOSPHATE AND PHENYL N-METHYLCARBAMATE, WHEREIN SAID COMPONENTS ARE PRESENT IN THE RATIO OF ABOUT FOUR PARTS OF SAID CARBAMATE PER PART OF SAID THIOPHOSPHATE. 